The present invention relates to a device for sensing multiple gas species to provide real-time in situ determination of the operation of important processes, including heat treating furnaces. Once these data are obtainable, real time control of the process becomes feasible.
Prior methods do not permit real-time in situ detection and analysis of the various gas species present in a heat treating furnace. This inability to detect and analyze results in an inability to precisely control, resulting in waste of energy and materials and needless pollution. A variety of prior art techniques take off a slip stream of the gas for analysis. Such slip stream analyses require that the gas sample be cooled, possibly resulting in changes in the gas composition. Further, the time inherently involved in isolating and cooling the gas sample results in a time lag, which prevents real time in-situ analysis.
It is therefore, desired to provide a method for detecting multiple gas species in a combustion operation and to provide data in a real-time manner for controlling important process variables. Such a method comprises the steps of: a) providing the flow chamber with a window transparent to light in the visible spectrum; b) focusing an incident beam from a monochromatic light source on a point internal to the flow chamber through the window; c) collecting a scattered light beam from the flow chamber passing external to the flow chamber through the window; and d) analyzing the intensity of the collected scattered beam in at least one characteristic frequency for each of the at least one diatomic gases. It is preferred to bring the incident beam proximate to the window in a first fiber optic cable and to collect the scattered beam proximate to the window in a second fiber optic cable. The method may be conducted when temperatures at the focal point of the incident beam are in excess of 250xc2x0 F., and more particularly, in excess of 1000xc2x0 F.
The preferred monochromatic light source is an argon ion laser with a wavelength of 514.5 nm. The preferred diatomic gas for being sensed with this method is a mixture primarily including carbon monoxide, hydrogen and nitrogen, with small amounts of oxygen being also capable of being sensed.